1. Field of the Invention
The present invention relates to a cleavage (cell division) promoter, as well as a fertilized or unfertilized ovum treated with the cleavage promoter, and methods for promoting cell division and increasing embryonic selection and shortening pregnancy.
2. Discussion of the Background
Reproduction in higher animals starts with the fusion of the gametes, followed by a definite period inherent to each species, the so-called pregnancy, and finally the delivery (hatching) of the offspring. The reproduction efficiency does not naturally reach 100%. This means that not all contacts between ovulated ova and sperm cells will actually lead to delivery, also defined as embryonic selection.
The reproduction efficiency is 30% or less in humans and approximately 70% in livestock such as swine, bovine etc. Another natural limitation of development and breeding of livestock is the pregnancy period being definite and characteristic for each species.
Improvement in embryonic selection and shortening of pregnancy period would be therefore of great industrial interest, particularly in the field of the livestock industry. On the other hand, the practical and scientific importance of in vitro fertilization for producing transgenic animals, fertilizing externally, etc. has steadily increased. However, up to the present invention success and recovery of in vitro fertilizing experiments have been poor due to insufficient preserving and unefficient development of fertilized or unfertilized ova.
Thus, there remains a need for cell division promoters or cleavage promoters capable of improving the rate of embryonic selection and in vitro fertilization and capable of shortening the pregnancy period.